Method of securing needle bearings in nylon gears



United States Patent METHOD OFSECURING NEEDLE BEARINGS'IN NYLON GEA'RS Herbert W. Harris, Racine, Wis., assigner to .Racine Industrial Plant, Inc., Racine,.Wis., a corporation Application March.19, 1956, Serial No. 572,405 1 Claim. (Cl. 29149.'5)

This invent-ion appertains to bearings and moreI particularly to a new and improved| method of securingl needle bearings in nylon gears.

Much diculty has been experiencedin the pastzihinsertingk and retaining needle bearings in nylon. gears. Invariably the needle bearings work out of thetliub and in order to prevent this, it has been the practice'- to= provide various types of end `stop-s and also, attempts. have been made to mold the gear around the gearing.: However, these methods have either not worked satisfactorily or have proven too expensive and complicated for practical purposes.

Therefore, one of the primary objects of my present invention relates fto a novel process for inserting and retaining the needle bearing or bearings in the hub of a nylon gear.

Another important object of my present invention is to provide a novel means for softening the end termination of the hub of the nylon gear to cause the nylon to flow inwardly against the ends of the bearings thus se curing the bearing rmly in the hub of the gear.

Still another object of my present invention is to provide a novel spinning tool which may be brought down against the opposite end of the nylon gear hub and generate heat in such a manner as to cut and soften the nylon so that it ows inwardly against the opposite end of the needle bearing thus securing the bearing to the gear.

A salient feature of my invention resides in the'fact that the spinning Itool is provided with a projecting portion or pilot which extends into the needle bearing to center the tool when the bearing is in the gear hub.

A further object of my invention resides in providing my spinning tool `with a peripheral cutting edge above the pilot and of such a size and configuration that when the tool is rotated in a drill press or other machine at high speed, this peripheral edge will generate heat by friction with 'the nylon and soften the same as it cuts so that the nylon will flow inwardly and firmly secure the bearings in place.

A further important object of my invention is: to provide a method for inserting any type bearing in a thermoplastic body utilizing a suitable Itool and heat application whereby the softened material will llow around the bearing ends to nish and hold the bearing to and in the body.

Still another object of my invention is to provide a simple, practical and reliable method land construction that is economical to practice, making the gear easy to assemble and positive in its operation.

With the above and other objects in view which will more readily appear as the nature of the invention is better understood, the same consists in the novel method, construction, combination and arrangement of parts hereinafter more fully described, illustrated and claimed.

A preferred 'and practical embodiment of my invention is shown in the accompanying drawings, in which:

Figure 1 is a side elevational view in section showing Patented Sept. 29, 1959 2 the spinning tool, nylon gear, needle bearings and the means utilized fory inserting the bearing in the gear hub with one end` of the gear hub finished by my novel method.

Figure 2 is a fragmentary side elevational view similar to Figure lV of the drawings but showingthe novel spinning tool in its operative position for finishing the other end of the gear hub.

Figure 3` is a fragmentary sectionalr View through the hub showing the needle bearings rmly secured in place with both ends of .the hub nished and turned inwardly about the bearings, the spinning tool being removed, and

Figure 4 is a fragmentary top plan view of the hub Asection of the nylon gear partly in section and illus trating the needle bearings firmly locked in their proper. position.

Referring now to the drawings in detail twherein, similar reference characters designate corresponding parts throughout the several views, the letter N generally indicates a nylon gear of the type nowy on the market and the same forms no particular part of my present invention but' for the purposes of description, the same includes a body portion 10V having a central hub opening 11' to receive one or more of the conventional typeneedle bearings 12" and 13. Obviously,- the number of needle bearingsutilized depends on the size ofn the nylon gear N, however, if more than one bearing is used, Iprovide a spacer 14 between each bearing.

As previously noted, my invention appertains primarily to a novel method for securing the needle bearing or bearings 1in proper position in the hub 11 and to facilitate the forming of the end portions or stops 15 and 15', I provide a novel spinning tool T which includes a chuck portion 16 adapted to iit in any type of rotating mechanism such as a drill press. The main body 17 of the tool T has its lower end 18 provided Iwlith a curtting and turning edge 19` and an annular stop shoulder 25. The end opposite the chuck 16 is provided 'with a centering portion or pilot 201 which fits Within the hub of the needle bearings 12 or 13 as shown.

In practicing my novel method, the pilot 20 of the tool T is provided with a iller sleeve 26 which is slipped over the pilot 20 as shown in Figure 1 and then the pilot is inserted in a bearing as shown; the bearing is, in turn, inserted in the hub opening 11 and the peripheral edge 19 of the tool and shoulder 27 of the filler sleeve 26 is brought into contact with the surface 21 of the hub H. With the bearing now in place, the filler sleeve is removed and the tool is again brought down and the pilot is received in the bearing. The tool is rotated at a relatively high speed and the friction generated by the ftool rubbing against the nylon softens the nylon and causes the same to flow inwardly against the end of the upper needle bearing 13 to form the upper end portion or stop 15' as shown more clearly in Figure 2 of the drawings. The stop shoulder 25, of course, limits the downward travel of the tool T but 'I may provide means in the machine for limiting the downward travel of the tool.

Obviously, the lower stop 15 has been previously formed by the same method, that is by inserting the pilot 20 in the lower bearing 12 forcing this bearing into the hub opening 11 and turning and forming the lower stop 15 by bringing the cutting and turning edge into contact with the end 22 of the nylon hub. In this manner, the needle bearings 12 and 13 are rmly secured in the hub of the nylon gear and cannot work loose or out of the hub. It should be noted also that the edge 19 of the tool T has only its inner wall 23 beveled and this bevel forms a guide which turns the softened nylon inwardly to ow around the ends of the bearings (Figure 2).

-If desired, however, although not preferred, the nylon gear N may be pre-formed or molded with the one end 22 already provided with the stop 1S as shown in Figure 1. If this be the case, then both bearings 12 and 13 and the spacer 14 are inserted from the end 19 onlyof the hub opening 11. Bearing E1-2 will then be forced against the inner end of stop 415 and only the upper stop 15' will be formed in accordance with my above described novel method.

In any event, the bearings are of such a size and conguration in relation to the hub opening 11 that they will t snugly and tightly into the hub and some force must be exerted to insert the bearings in the hub. Also, great stress is laid to the fact that the nylon is softened as a result of fthe heat generated by the friction resulting from the contact of the cutting or turning edge 19 with the nylon. Not only then is the annular Way or peripheral groove 24 formed in the hub ends 21 and 22 but the nylon thus softened is turned inwardly due to the aforementioned inner slanting edge 23 of the spinning tool T. Of course, a stationary tool may be used in lieu of my novel spinning tool and heat may be applied in any known manner to soften the thermoplastic material, but I prefer to use a spinning tool with friction as above described.

From the foregoing, it is believed that the features and advantages of my invention will become readily apparent to those skilled in the art and it will, of course, be understood that changes in the form, portion and minor details of construction may be resorted lto without departing from the spirit of the invention or the scope of the appended claim, I claim:

A method of inserting and retaining a bearing and its casing in the hub opening of a rotatable thermoplastic member including, the step of inserting a spinning tool pilot in the bearing forcing the bearing and its casing into the hub opening and bringing a peripheral cutting edge of the tool in Contact with one end termination of the hub opening and turning the spinning tool at high speed to generate heat by friction and owing the said end termination of the hub inwardly around the bearing end Whereby the bearing will be securely retained in the hub opening of the rotatable member.

' 'References Cited in the le of this patent UNITED STATES PATENTS 1,903,776 Clark et al. Apr. 18, 1933 1,976,019 Heim Oct. 9, 1934 2,169,315 Yngve Aug. 15, 1939 2,198,831 Moyer Apr. 30, 1940 2,349,281 Kendall May 23, 1944 2,355,511 Cobb Aug. 8, 1944 2,427,072 Rubin Sept. 9, 1947 2,449,247 Paucek Sept. 14, 1948 2,572,956 Servis Oct. 30, 1951 2,619,912 Shames Dec. 2, 1952 V2,699,656 Anderson et al Ian. 18, 1955 2,720,119 Sherman Oct. 11, 1955 

